Chemists have developed a process to transform CO2 into methane (and potentially fuel)

Currently, as the effects of global warming are increasingly felt, reducing the carbon footprint remains one of the most important issues. While some researchers have developed an electro-synthetic biodiesel that is significantly more efficient and cleaner than existing alternatives, others are exploring the transformation of carbon dioxide into methane. American chemists have thus developed an effective method for capturing and converting CO2 into CH4. According to them, this advance using electrochemistry opens the way to the transformation of carbon dioxide into alternative fuels.

In the context of the fight against greenhouse gases, many researchers are now focusing on energy innovations, such as the conversion of CO2 into methane. Last June, researchers at the Daegu Gyeongbuk Institute of Science and Technology (DGIST) in South Korea developed technology capable of carrying out this process with an efficiency of 99.3%, which is remarkable compared to current methods which struggle to exceed 70%. This technology is based on photocatalysis, a process using light to accelerate a chemical reaction.

The South Korean team used a photocatalyst composed of cadmium selenide and amorphous titanium dioxide (TiO2). Cadmium selenide was selected for its ability to efficiently absorb visible and infrared light, while the disordered structure of amorphous TiO2 optimizes charge transfer while ensuring chemical and thermal stability. Although this innovation represents a step forward towards a sustainable solution to global warming, its large-scale deployment remains to be determined.

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At the same time, other conventional CO2 capture systems aimed at transforming it into useful products are under development, but still require a considerable amount of energy to be implemented industrially. However, researchers at Ohio University have discovered a way to save this energy by directly transforming captured CO2 into methane.

Nickel atoms as an innovative catalyst

According to Tomaz Neves-Garcia, lead author of the new study and a postdoctoral researcher in chemistry and biochemistry at Ohio State University, the key to this new method is the use of a nickel-based catalyst, rather than a photocatalyst. The team directly targeted the captured form of carbon dioxide, carbamate.

In their work, published in the Journal of the American
Chemical Societythe researchers explain having used nickel atoms arranged on an electrified surface. They found that this catalyst allows carbamate to be directly converted into methane. “ We are moving from a low energy molecule to a high energy fuel, which is advantageous because it releases more usable energy during combustion ” Neves-Garcia said in a statement. “ What makes this so interesting is that others capture, recover and convert carbon dioxide in multiple steps, while we save energy by doing these steps simultaneously “, he added.

This method is therefore the first to exploit electrochemistry to convert carbamate into methane. “ Methane can be a very interesting product, but more importantly it opens the door to processes to convert captured CO2 into other products, such as methanol or more complex hydrocarbons. “, explains Neves-Garcia. The researchers believe that this approach could in some way contribute to “closing” the carbon cycle. Indeed, once burned, methane emits CO2 which, captured and reconverted into CH4, creates a continuous cycle of energy production, thus limiting its impact on global warming.

The team now plans to explore other chemical alternatives, both clean and sustainable, to capture atmospheric carbon. “ We must strive to minimize the energy spent on carbon capture and conversion
», underlines Neves-Garcia. “ So, instead of performing all capture and conversion steps separately, we can combine them into a single step, thus avoiding energy-intensive processes », he concludes.

Source : Journal of the American Chemical Society